Acute care facilities rely on rigid containers for the sterilization, handling and storage of surgical instrumentation and supplies. It is imperative that after sterilization, the sterile surgical instruments and supplies not be exposed to contaminates while still in the sterilization container.
Rigid sterilization containers commonly have a filtered vent (or vents) in the lid or other part of the container consisting of a patterned group of small holes. The floor of the container may also have a vent (or vents) which usually mirrors the number, size and placement of the vent or vents in the lid. See, for example, my U.S. Pat. No. 6,319,481 B1. Typically, each vent will have a sheet filter that covers the vented area and is held in place by a locking filter cover.
One commercially available sheet filter suitable for use with the present invention and with sterilization protocols is a 1.4 osy (ounces per square yard) basis weight Securon SMS manufactured by BBA Non-Wovens. Other suitable sheet filters are also commercially available. These special filter materials are characterized by the property that they are porous at elevated temperatures to allow sterilization media to pass and non-porous at lower temperatures.
Thus, the vent, with the filter element held in place by a filter cover, allows for the entry of the sterilizing media and exit of the displaced atmosphere during the sterilization cycle. Following sterilization, the filter provides a bacterial barrier to protect the sterile integrity of the contents during storage and transport.
As the sterilizing media is introduced into the sealed container, condensation can form and collect inside the container. Retained moisture in the form of condensation may be a by-product of either steam autoclaving or alternative low temperature sterilization methods.
In addition to steam autoclaving, “flash” processing is a commonly used method of rapid steam sterilization. Since “flash” steam sterilization protocols have either a limited or no drying cycle, retained moisture is a persistent condition. Since bacteria have no form of self-propulsion or locomotion, they need fluid pathways or small particles as a vehicle or conduit for their movement and/or dispersal.
Whenever there is retained moisture and the floor of a container is vented, the bacterial barrier properties of the filter assembly may be immediately compromised when exposed to a non-sterile atmosphere, while still at an elevated temperature (e.g., when the sterilization container is removed from the sterilization chamber).
This situation is of special concern when retained moisture is present and the containers are handled, stored or transported while they are still hot. Containers with vented bottoms are at particular risk of contamination due to the occurrence of undetected leaking of fluid around (or through) the vents when the contents are assumed to be sterile.
Consequently, rigid sterilization containers that do not form a fluid-proof seal, as well as a particulate seal, around the filtered vents are seriously limited and may be inappropriate for the multiple sterilization methods utilized by acute care facilities.
Seals currently used for filter vents for sterilization containers are unprotected and subject to damage, which can form fluid pathways which compromise their integrity, making the containers unsafe for multiple uses.